Genome-wide STRs and American prehistory

This study examines a genome-wide dataset of 678 Short Tandem Repeat loci characterized in 444 individuals representing 29 Native American populations as well as the Tundra Netsi and Yakut populations from Siberia. Using these data, the study tests four current hypotheses regarding the hierarchical distribution of neutral genetic variation in native South American populations: (1) the western region of South America harbors more variation than the eastern region of South America, (2) Central American and western South American populations cluster exclusively, (3) populations speaking the Chibchan-Paezan and Equatorial-Tucanoan language stock emerge as a group within an otherwise South American clade, (4) Chibchan-Paezan populations in Central America emerge together at the tips of the Chibchan-Paezan cluster. This study finds that hierarchical models with the best fit place Central American populations, and populations speaking the Chibchan-Paezan language stock, at a basal position or separated from the South American group, which is more consistent with a serial founder effect into South America than that previously described. Western (Andean) South America is found to harbor similar levels of variation as eastern (Equatorial-Tucanoan and Ge-Pano-Carib) South America, which is inconsistent with an initial west coast migration into South America. Moreover, in all relevant models, the estimates of genetic diversity within geographic regions suggest a major bottleneck or founder effect occurring within the North American subcontinent, before the peopling of Central and South America.

52 comments:

Western (Andean) South America is found to harbor similar levels of variation as eastern (Equatorial-Tucanoan and Ge-Pano-Carib) South America, which is inconsistent with an initial west coast migration into South America.

Why? The distance between the two coasts is extremely narrow at Costa Rica and specially Panamá. It's absurd to assume that Western coastal dwellers could not cross to the Caribbean coasts just too easily before entering South America.

Otherwise this narrowing of the land at Central America is also totally consistent with a founder effect or series of them: as people moved south they had less and less land to live in, and all South American founders must have lived at some time in Central America, so their gene pool to begin with was restricted even before entering the southern continent.

Their conclusions come from the STR data. The old adage applies: a picture is worth a thousand words. It would have been better to show their interpretation of movement of peoples in North, Central and South America. Why are certain South Amerindians much darker than others? The skin pigmentation change would have required time and adaptation for that increased pigmentation to occur.

In my humble opinion, the intellectual capabilities of peoples of the "Stone Age" are always underestimated. Those Amerindians may have used boats to populate Central/Caribbean/South America in a saltatory fashion similar to how Neolithic peoples settled in Mediterranean Europe and North Africa from Cyprus to Portugal in the Atlantic between 10 and 7 kya.

Why are certain South Amerindians much darker than others? The skin pigmentation change would have required time and adaptation for that increased pigmentation to occur.

The differences are not that big. They are all in the dark white to light brown range, excepting some very admixed communities like Mapuches. The variation in this aspect is in any case much smaller than what we find in Eurasia.

"Those Amerindians may have used boats to populate Central/Caribbean/South America in a saltatory fashion".

I recently read somewhere that Amerindian arrival on the Caribbean islands was quite recent, relatively speaking. Something like 5000 years ago. Argues for the recent development there of open water travel and so against arrival in America by boat. I'll try to find more information regarding Carribean settlement.

Coastal and riverine navigation with, say, canoes would not allow to settle the Antilles, excepting Trinidad.

I have read that the Caribs (Arawaks) or maybe the older colonists: the Tainos, were possibly the first ones worldwide to use the triangular sail, adopted by Europeans soon after the arrival to America.

Whatever the case there is a substantial difference between a canoe and the much more mariner sailing boat, regardless that you like to dump everything in the same tin, using the ambiguous term "boating" for all. Canoeing is very old but does not normally allow for any adventuring in open seas (extremely risky), sailing instead is rather recent and does allow for such travels.

"Canoeing is very old but does not normally allow for any adventuring in open seas".

Exactly. So arrival in America by sea is very unlikely. I'm pretty sure the pre-European Polynesians used a triangular sail for ocean travel. And dugout canoes may not be very old either. They require a major effort to make if using just stone tools (even with metal tools really). The appearance of adzes may indicate the development of dugouts, somewhere around 7-8k. Before then canoes were probably skins or bark stretched over a framework of branches or simply bundles of reeds or bark tied together.

"No pre-7,900 year ago (7,000 rcbp) sites were noted in the 1963 theme study for either the Greater or Lesser Antilles islands (Haag 1963:337)".

Source:

http://www.nps.gov/seac/outline/06-carib_prehistory/index.htm

"Nearly 6,000 years ago, people took the bold step of paddling their canoes out beyond the horizon of the Caribbean Sea, where no land could be seen. They were well rewarded for taking this risk, for they found a large, rich, and uninhabited chain of islands that stretched 1,500 km and contained more than 200,000 sq km of land. It was the last large area of the Americas to be explored and populated. These discoverers and their descendants have lived in the Caribbean ever since".

You like to mix things. Coastal migration does not mean "by sea", though in some stretches like swamps, bays, rivers, coastal island chains... it may imply some navigation.

It's mainstream and consensual that people first (and second and third) arrived to America via Beringia, which was then a wide isthmic area. Now, it's very possible that the first Beringians, as well as the first Americans at a later date, followed the richer coastal areas and that does imply certain level of at least basic boating skills.

And dugout canoes may not be very old either. They require a major effort to make if using just stone tools (even with metal tools really).

That's a fetish you have. Most peoples who historically have used simple dugout canoes were stone tech users. Of course there are other, maybe easier, possibilities like the skin-made kayaks of Inuits, rafts, etc. But I don't see why dugout canoes would be so complicated.

Interesting stuff and still so few is known.Here some general rambling from a South American, I don't know if it may help.

- The jungle together with high mountains would initially pose quite some barrier throughout a large part of Colombia, Venezuela, Brazil (but the grasslands very inland). I imagine groups going initially preferably along Pacific and Carib coastlines, at least for quite some time. Very few places close to the coasts for a huge region were anything but thick jungle.

- Language variation in South America is higher than in other parts of the Americas (well, most languages have died out now and others dying every year, but they are still there, there were over 1500 in South America when Europeans arrived). We know the Ice Age swept across a big part of North America, but perhaps it should be higher in central America.

- There is indeed a lot of variation in skin color, not as between a Swede and a person from ceylon, but perhaps between Spaniards and Swedes, even if there are not like blonde or green-eyed versus brown eyed.

Most Europeans know mainly Indians from the Inca area of influence and from Mexico to Guatemala. Even Columbus noticed it when he arrived to what is now Venezuela (third trip, 1498). It is not just the colour of the skin, but height and form of the nose (the typical Inca nose is unknown in Venezuelan Indians, for instance, form of skull, eye form more or less slanted). Even within Venezuela we see differences between, say, the Guajiros (Wayúu) and others like the Pemones (from a Carib group to the Southeast, around where the Auyan tepui - aka as Angel's Falls - is), Waraos.

- There are few haplogroups in the Americas, though (A, B, c, D and X, Q), but I don't know how variation compares to other regions.

- Carib Indians were not Arawaks. These are quite two different main groups with different language families. Arawak Indians were living in the whole Caribbean and a lot of what is now Venezuela's East and a bit of the centre. Carib Indians started to expand from the Amazon towards the North. They settled across the Orinoco, started to expand in what is now East and central Venezuela and along the Antilles going northwards, attacking the Arawaks.Arawak and Carib Indians have two different language families.When Spaniards arrived, Carib Indians were expanding raiding the Arawak Islands in the Antilles and in what is now Venezuela (from the Arawak fear and the Spanish interests, perhaps based on some habit, real or not, we get the Cannibal story).

- It is said the Amazon was very highly populated ages ago and population somehow collapsed but that may have happened at the time the European invasion started.Here an article in German on the forgotten cities of the Amazon: http://www.welt.de/wissenschaft/article2367593/Die-vergessenen-Staedte-Amazoniens.html(perhaps you can use language tools to get a rough translation if you don't read German)

It means that near enough. We've already argued about how difficult it is to actually follow the coast in any meaningful manner for any distance anyway. Ponto specifically said, 'Those Amerindians may have used boats to populate Central/Caribbean/South America'. I was merely pointing out that it was unlikely that they used boats as a major component in any 'migration', either into America or along its coast.

"Most peoples who historically have used simple dugout canoes were stone tech users".

But they made dugouts using stone adzes. It's labourious enough to make dugouts with adzes but almost impossible without them, therefore adzes in the lithic record tend to indicate ability to make dugout canoes.

"Of course there are other, maybe easier, possibilities like the skin-made kayaks of Inuits, rafts, etc".

True. But you seem to believe coastal navigation is an extremely simple matter. Coastal waters are often very difficult and dangerous places. In Paleolithic times coastal boating would have been more comparable to using a surfboard rather than anything like a motorised boat or sophisticated sailing vessel. It's extremely unlikely Paleolithic people had the expertise that Inuits have in manouvering their kayaks. Kayaks appear to be a fairly recent invention. So, any Paleolithic 'coastal migration' theories are rubbish.

Coasts have the advantage of providing several steady, independent sources of food and water. Still, coastal migration is not something that that takes place at a fast scale or only involves the first 100 meters. So, navigation skills necessary can be quite basic. And for much of the Americas, coastal migration would have been the only possible route,anyway.

As to the dugouts, controlled burning of the inside makes this a much easier task - even with simple stone tools.

Using the food the sea and rivers provide, in addition to hunting animals within many tens of kilometers inland of both, gives a huge advantage in sustenance - also during bad times. In the North, say up to northern California on the West coast, this is much easier because of reliable fresh water sources and relatively benign plant growth inland - also 15,000 - 20,000 years ago. It becomes easier again in tropical areas.

As in the ice age Mediterranean, at in-between latitudes the very dry "sagebrush/chaparral" provides very little food and water, and makes any movement extremely difficult. So, I would assume that a larger number of people migrated through the central and eastern part of North America (east of ~110 degr.), below a certain latitude (~40 degr.)

So, quite likely the first migrations turned in larger numbers inland somewhere south of the ice sheets, where water sources where available and many grazing animals for easy hunting (similar to west Asia and Europe, in many regions animals had not previously encountered humans as hunters, so the first wave of people could easily take advantage of this situation, but then needed to move on).

In Mexico except Baja, and south of it, coastal migration and settlement alongside rivers would have been the preferred route, again. Down to about Peru on the west coast, where far inland food and water sources again become more favorable.

I was merely pointing out that it was unlikely that they used boats as a major component in any 'migration', either into America or along its coast.

You are first saying that you admit kayaks or rafts as plausible (you have an issue with dugout boats, ok) and then say that you don't think they could have used them in their SLOW migration along the American coasts? Please!

Remember that Australasia had already been colonized long before and that for the colonization of that continent, NECESSARILY, they used some sort of boats.

But they made dugouts using stone adzes. It's labourious enough to make dugouts with adzes but almost impossible without them, therefore adzes in the lithic record tend to indicate ability to make dugout canoes.

I understand they are made by basically burning the trunks in a controlled manner. The biggest problem may be to pull down the tree without proper axes (but you can in fact cut some trees with little more than a knife a rock and patience - and these would surely be the best to make canoes). Anyhow to remove the burnt wood could be done with digging sticks or whatever.

But whatever the techniques the main problem is that the same style of boat is found throughout the world: Africa, Europe, Native America, New Guinea... so either we face a very unusual case of multiple convergent technological evolution or it's something that was used everywhere where trees grew since "always".

True. But you seem to believe coastal navigation is an extremely simple matter. Coastal waters are often very difficult and dangerous places.

I know first hand. That doesn't mean that people has not used boats where possible. Obviously basic boats are not meant for coastal or open seas navigation but first and foremost for rivers, swamps, estuaries and lakes/lagoons, which are obstacles that are best saved using something like a boat. Of course you can also go offshore to fish or whatever in good weather.

Paleolithic people surely used boats in all humid and coastal environments according to their needs and skill. Probably if they had to overcome a cape, they went by land but if they had to cross an estuary, bay or swamp they crossed by boat. My best guess anyhow.

Whatever the shortcomings of boats, they are a zillion times better than swimming.

It's extremely unlikely Paleolithic people had the expertise that Inuits...

Historical Inuits were Paleolithic people: hunter-gatherers with stone and bone tools. Together with Bushmen, Pygmies, Australian Aboriginals and a handful of Siberian peoples like the Nganasan, they are the only modern example we have of Paleolithic hunter-gatherer lifestyle.

Actually the similitudes are so intense that I think they are good model to explain European Magdalenians, for example, of whom we know that ate sea mammals, used whale bones and had harpoons extremely similar to those used by Inuits.

Kayaks appear to be a fairly recent invention.

Are they?

I really hate people who think hunter-gatherers were apelike idiots, you know. In the Paleolithic there were a lot of refined technologies, like needles to sew clothes properly, fishing hooks, harpoons efficient enough to catch sea mammals and loads of other cool stuff. And surely efficient boats too.

We have a distorted perception of Paleolithic because only hard stuff like rocks and bones is normally preserved but obviously these materials comprise only a tiny fraction of the actual materials used. Wood, leather, bark and vegetable fibres are not preserved, nor are poisons or medicines, or plants or even the bones of the smaller animals they actually ate. So we are missing a lot of the actual picture. And that includes boats, always made of perishable materials.

True. But they were not all invented at the same time, or all carried from a central region. People progressively made improvements to their existing technology as the particular culture used them more and more. Needles, clothes, fishing hooks, harpoons and boats were not invented fully efficient but were improved with time and experimentation.

"You are first saying that you admit kayaks or rafts as plausible".

It is extremely unlikley that kayaks, with the top sealed over, are an ancient Paleolithic boat. Rafts, yes. Although, as you say, technically Inuits were Paleolithic people their technology for surviving extreme cold was very advanced. Relevant in this case: especially their use of sewing. We cannot compare their boats with those of earlier humans, at least in any meaningful way. Rafts are not particularly useful for travel ALONG a coast, although they can be used to move out for the shore and back again in calm waters.

"Actually the similitudes are so intense that I think they are good model to explain European Magdalenians, for example, of whom we know that ate sea mammals, used whale bones and had harpoons extremely similar to those used by Inuits".

Were Magdalenians really Paleolithic? They used to be refered to as Mesolithic. They're certainly relatively recent.

"Remember that Australasia had already been colonized long before and that for the colonization of that continent, NECESSARILY, they used some sort of boats".

Not 'Australasia' but Australia. There is a world of difference. The geographical extremities of Australasia were not colonized until a mere eight hundred years ago (for example New Zealand). So the progressive expansion through Australasia took at least 50,000 years. The expansion was gradual, presumably because of progressive improvements in boating technology, including the development of the dugout, the outrigger and sails.

"Obviously basic boats are not meant for coastal or open seas navigation but first and foremost for rivers, swamps, estuaries and lakes/lagoons".

So how did people manage to reach Australia/New Guinea across open seas? Through Wallacea obviously, but isn't that open sea? That's where it gets really interesting. At times of lowered sea level Wallacea becomes a chain of virtually landlocked, and therefore relatively calm, seas. From the north: South China, Sulu, Celebes and Banda, although the last less so. As people in the region became more adventurous in their boats some were carried far away.

"the main problem is that the same style of boat is found throughout the world: Africa, Europe, Native America, New Guinea... so either we face a very unusual case of multiple convergent technological evolution or it's something that was used everywhere where trees grew since 'always'".

Always? I suspect that once invented dugouts were so useful that the technology spread. In fact I'd go so fart as to suggest that the invention contributed to several haplogroup expansions.

"I understand they are made by basically burning the trunks in a controlled manner".

Felling the tree is the first step, as you say. Controlled burning is the second. But the burnt wood is usually, and certainly most easily, removed using hafted adzes.

"Coasts have the advantage of providing several steady, independent sources of food and water".

That is far from being universally true.

"Using the food the sea and rivers provide, in addition to hunting animals within many tens of kilometers inland of both, gives a huge advantage in sustenance - also during bad times".

And once humans had begun utilising 'many grazing animals for easy hunting' they would have little reason to return to the coast, even in the unlikley event they had first entered along it.

"in many regions animals had not previously encountered humans as hunters, so the first wave of people could easily take advantage of this situation, but then needed to move on)".

But again they would have moved to new regions containg similar resources rather than return to the coast. I'm quite prepared to accept they had the technology necessary to use rivers and lakes in their movements but the exposed coast?

What is the problem with moving along the coast? In the Americas it meant going South, South, South, for a long time.I reckon the movement Eastwards was more problematic in many occasions.The problem with going South, though, is that the landscape kept changing. A rapid transfer of technologies once "things started moving" was not as easy as in Eurasia, if we follow Jared Diamond's hypothesis (which I do to a big extent).

Relevant in this case: especially their use of sewing. We cannot compare their boats with those of earlier humans, at least in any meaningful way.

Needles are known since very early in cold climates like that of Ice Age Europe. The "naked ape" would have been unable otherwise to survive in the steppe. Surely this applies to Beringia and nearby areas as well.

Were Magdalenians really Paleolithic? They used to be refered to as Mesolithic. They're certainly relatively recent.

Not "mesolithic" at all. Magdalenian (and Epigravettian in Italy and Eastern Europe) are synonymous of Late Upper Paleolithic. The term "Mesolithic" is used by some to mean Epipaleolithic: hunter-gatherer cultures of post-glacial times (for many the term "Mesolithic" only applies to cultures in transition to Neolithic, like the cereal gatherers of West Asia and maybe the Nile). In Europe these Epipaleolithic cultures show some clear differences like increased dependence of coastal foraging, microlithism and probably loss of rock art. In any case Epipaleolithic cultures are nothing but the last Paleolithics.

Not 'Australasia' but Australia. There is a world of difference.

Say Sahul. I could not care less.

So the progressive expansion through Australasia took at least 50,000 years.

Not progressive: two different processes in fact.

The expansion was gradual, presumably because of progressive improvements in boating technology, including the development of the dugout, the outrigger and sails.

Nonsense! The colonization of Sahul is almost totally unrelated to that of island Oceania: they are separated by maybe 40,000 years or more, they imply totally different "boating" capabilities, and they were carried on by different peoples.

So how did people manage to reach Australia/New Guinea across open seas? -

You tell me. My best guess is that there were volcanic islands that do not exist anymore. Still island hopping may had been possible to New Guinea even with the current geography (but much lower sea levels).

But, in any case, that is the mystery, not coastal boating, kayaks or dugout canoes.

But the burnt wood is usually, and certainly most easily, removed using hafted adzes.

Adzes offer increased performance, that's clear, but other methods could be used anyhow, like the universal "digging sticks".

"Coasts have the advantage of providing several steady, independent sources of food and water".

That is far from being universally true.

If you can fish or forage seafood (like combing beaches), most coasts are very favorable environments. Rivers are also interesting. That's why people everywhere has always tended to live near waterways - and we still do nowadays.

And once humans had begun utilising 'many grazing animals for easy hunting' they would have little reason to return to the coast, even in the unlikley event they had first entered along it.

May I remind you about the several recent studies that strongly suggest that H. sapiens was not a specialized large mammal hunter like Neanderthals but rather a versatile forager that ate loads of fish or other aquatic food. Coasts and rivers provide when everything else fails. Additionally fresh water attracts large and small land animals, birds, etc.

But again they would have moved to new regions containg similar resources rather than return to the coast.

Why? If they lived better off the coastal resources and had already become adapted (these migrations took many many generations), why would they return to the harsh life of the steppe?

That for Terry UP people were some sort of dumb beings unable to innovate as need required. He assumes that they crossed rivers, swamps and straits by mere swimming and that therefore these posed a major barrier, along with the often rugged coastal terrain. He thinks that walking and swimming was all they could do, even if indirect evidence once and again says otherwise.

He also has a fetish that all global mariner technology of any sort was developed in an area he calls "Wallacea", between Asia and Australia. He can't accept that people must have used some sort of boats since the very first time they exploited a swamp or riverine area. For him crossing Bab-el-Mandeb was impossible, no matter that a few milennia later the same people crossed a much wider sea gap into Sahul.

It's his fetish idea: that "Wallacea" was itself a mariner process and that the rest of the world learned from them somehow.

The problem with going South, though, is that the landscape kept changing.

I've thought a bit about this. I presume that initially, going south was just natural: warmer climate, better opportunities. The main problems (partial barriers) may have been when they reached desertic or very dense jungle areas. Jungles provide everything but need an adaptation, deserts may only be habitable if the coast provides.

Not sure which was the climate of America in the Ice Age but I imagine these climatic areas would cause the expansive drive to slow down and could help explaining some founder effects.

Moving along the coast is no simple matter, as you would know if you've tried to walk very far along it. Or tried to move along it offshore in any sort of basic boat.

"The problem with going South, though, is that the landscape kept changing".

Makes it neven more complicated than moving along the coast at the same latitude.

"The term 'Mesolithic' is used by some to mean Epipaleolithic: hunter-gatherer cultures of post-glacial times ...In Europe these Epipaleolithic cultures show some clear differences like increased dependence of coastal foraging, microlithism."

Call them what you will, they are still much more recent than the movement to Sahul. And you mention that coastal foraging increased in Europe in the Epipaleolithic? I see even bigger holes developing in your reasoning.

"Needles are known since very early in cold climates like that of Ice Age Europe".

That too is after humans had reached Sahul, so no sewn skins enclosing boats in that movement.

"Not progressive: two different processes in fact".

Sorry. Progressive. Not just two. You should read up on it.

"Adzes offer increased performance, that's clear, but other methods could be used anyhow, like the universal 'digging sticks'".

I've not heard anyone claim that the first people to cross Wallacea did so in dugout canoes, so dugouts must be at least more recent than 50,000 years. And probably much more recent than that.

"My best guess is that there were volcanic islands that do not exist anymore".

No need to postulate that. There are still plenty of islands in Wallacea (a commonly accepted term, by the way, even if unknown to self-centred Europeans).

"That for Terry UP people were some sort of dumb beings unable to innovate as need required".

That is the stupidest comment I've ever read from you, and I've certainly read some stupid ones. It is you who is convinced that modern human technology remained unchanged and unimproved from the moment they left Africa right up until a little more than 10,000 years ago, and then only in Europe. The second stupidest comment you've made is:

"that they crossed rivers, swamps and straits by mere swimming and that therefore these posed a major barrier".

I've said many times I accept ancient humans had the technology to cross relatively slow flowing rivers on primitive boats.

And you mention that coastal foraging increased in Europe in the Epipaleolithic? I see even bigger holes developing in your reasoning.

Why? It is a fact. Mollusk consumption clearly increased in the European Epipaleolithic. The piles of shells are a typical fossil of that period. Not just sea mollusks but surely the first recipes for escargots were also invented then.

This says nothing against their Magdalenian precursors not exploiting the seas, because there is enough evidence that they did.

That too is after humans had reached Sahul, so no sewn skins enclosing boats in that movement.

Lack of evidence is not evidence of lack. But, well, if they had dugout canoes... they surely did not need them.

Sorry. Progressive. Not just two. You should read up on it.

Two waves: one c. 50,000 BP, originated in Indonesia and another in post-Neolithic times, originated in Taiwan. There's a brutal gap among them.

I've not heard anyone claim that the first people to cross Wallacea did so in dugout canoes, so dugouts must be at least more recent than 50,000 years. And probably much more recent than that.

I have not read anybody on that either: neither in favor nor against. Dugout canoes are just too universal to be a recent development I understand.

t is you who is convinced that modern human technology remained unchanged and unimproved from the moment they left Africa right up until a little more than 10,000 years ago, and then only in Europe.

Not at all. Obvioulsy they improved and invented stuff but it's hard to know from the limited evidence available. We know of minimal dates but not of the actual ones.

I accept ancient humans had the technology to cross relatively slow flowing rivers on primitive boats.

More than just rivers: they crossed into Sahul very early on, remember? And anyhow a dugout canoe and a kayak are "primitive boats".

"Using the food the sea and rivers provide, in addition to hunting animals within many tens of kilometers inland of both, gives a huge advantage in sustenance - also during bad times".

And once humans had begun utilising 'many grazing animals for easy hunting' they would have little reason to return to the coast, even in the unlikley event they had first entered along it.

"in many regions animals had not previously encountered humans as hunters, so the first wave of people could easily take advantage of this situation, but then needed to move on)".

But again they would have moved to new regions containg similar resources rather than return to the coast. I'm quite prepared to accept they had the technology necessary to use rivers and lakes in their movements but the exposed coast?

We are talking about the Americas, here. Due to the ice sheets, there was no alternative to a coastal route until mid-latitudes. And with "coastal," no one means within a few 100 meters or even within a few kilometers. It always involves the adjacent land and river systems - both for living/resources and for migration. And, migration is what happens due to overpopulation or overuse of resources - so, most people, most of the time, remain in a defined area and environment and do not migrate.

As to specifics, I mentioned some geographical and climate aspects above. For NW America, clearly, somewhere around 40 degrees latitude, more people could (initially) live, multiply, and further migrate inland than along the relatively arid, barren, and difficult to pass through south-west coast. Conversely, once on either coast of Mexico, the coast would have been the preferred area of sustenance, settlement, and further migration. And so on.

"Dugout canoes are just too universal to be a recent development I understand".

I doubt if you could find anyone, anywhere, who would claim the first Australians arrived in dugout canoes. Rafts or bundles of reeds or bark are the means of transport most often suggested. The Aborigines occasionally used these basic watercraft on placid rivers, lakes and very sheltered harbours, but not on the open coast. Anyway, except for some groups in the far north who had presumably had contact with the maritime cultures of Indonesia and New Guinea, they did not possess dugout canoes when Europeans arrived. In New Guinea we do find human use of dugout canoes, and use of the coastal ecological niche. But the vast majority of these people speak Austronesian languages. In fact it is quite likely that an unoccupied coastal ecosystem is the factor that allowed the Austronesian expansion in the first place.

"And with 'coastal,' no one means within a few 100 meters or even within a few kilometers. It always involves the adjacent land and river systems - both for living/resources and for migration".

Again, apart from those of the far north, the Australian Aborigines were hardly notable users of coastal resources, other than shelfish and fish easily speared from land. And once more those Aborigines from the north were undoubtably influenced by contact with Austronesian-speaking people. And the coastal resources of Australia were hardly depleted by the time Europeans arrived so this can hardly be the reason for any abandonment of the apparently highly productive boat-using coastal culture you both claim allowed them to reach Australia in the first place ("If they lived better off the coastal resources and had already become adapted ... why would they return to the harsh life of the steppe").

"We are talking about the Americas, here".

So, what about America? Granted the cultures of the northwest were fairly maritime and had dugouts. But these people are almost without exception speakers of Na-Dene or Na-Dene-related languages. This language group is usually, although not universally, claimed to have arrived after the initial colonists. And within America, but outside that region, once more nowhere do we find the sort of coastal culture you two claim is of such ancient pedigree. It's hard to find any reason why it should have been so completely abandoned.

All in all the evidence seems to speak loudly against any 'coastal culture' likely to have supported any 'coastal migration'.

It can be argued though that Azilians at least continued the seagoing practices of Magdalenians (similar harpoons) and we do have several reasons to see Magdalenians using the sea one way or another (they ate sea mammals, they used whale bones, they had harpoons way to similar to those of Inuits...). And that is more or less at the time (19-10,000 BP) of the colonization of America (maybe 15,000 BP).

Anyway, except for some groups in the far north who had presumably had contact with the maritime cultures of Indonesia and New Guinea, they did not possess dugout canoes when Europeans arrived.

Native Americans did have them. So they had been invented by the time of the arrival to America most probably.

So, what about America? Granted the cultures of the northwest were fairly maritime and had dugouts.

In the Amazon too...

So, even if you are right re. Australia, it's quite clear that in the 20-30 thousand years between that migration and the one to America, dugouts and other "serious" boats (skin boats) became widespread.

Actually Native Americans by the time of European arrival were developed enough as to have regular naval trade between Mexico and Peru. Coastal, indeed. In the Caribbean, the sailboats were surely comparable to the Austronesian crafts.

And, even if all that is wrong, it's clear that people everywhere used some sort of boats regularly... just because they are a necessity: in the jungle you need boats to move along the rivers or to survive in the floods season, in the coasts you need boats to cross stuaries, bays and swamps, in the interior you need boats to cross rivers, just down the cave you live at, and in the Arctic you need boats just to be able to eat anyting at all an not get frozen when crossing water bodies. The only place where you do not need boats is in the vast inland deserts... but deserts were impossible to exploit before the domestication of the camel or at last irrigation agriculture.

"Native Americans did have them. So they had been invented by the time of the arrival to America most probably".

The second sentence doesn't necessarily follow from the first at all. Dugouts could easily have been introduced later and spread, even as far as the Amazon. It's just part of your 'fetish that all global mariner technology of any sort was' already developed by the time modern humans left Africa. You believe that no new technologies were invented after that time until the Magdalenian. Well, at least you believe that any advances must have happened in Europe.

"it's quite clear that in the 20-30 thousand years between that migration and the one to America, dugouts and other 'serious' boats (skin boats) became widespread".

I'd agree totally with the skin (and bark-clad) boats but I have serious difficulties accepting dugouts as being that ancient.

"In the Caribbean, the sailboats were surely comparable to the Austronesian crafts".

Again you're bringing up irrelevant information. We know from another of Dienekes' recent posts that humans didn't invade the Carribean until relatively recently.

"it's clear that people everywhere used some sort of boats regularly...".

No it's not. It's just your assumption. But boats of some sort had obviously been developed by 55k or so because people managed to cross Wallace's Line, but we really have no idea of boating's history before then. Next you'll be claiming that Home erectus had boats.

The second sentence doesn't necessarily follow from the first at all. Dugouts could easily have been introduced later and spread, even as far as the Amazon. It's just part of your 'fetish that all global mariner technology of any sort was' already developed by the time modern humans left Africa. You believe that no new technologies were invented after that time until the Magdalenian. Well, at least you believe that any advances must have happened in Europe.

Not at all. I just find very difficult that the dugout would have spread so easily my mere cultural diffusion to such remote areas after the populations had become essentially isolated from each other. I don't think Europeans invented anything in particular re. navigation in fact. That's an absurd accusation.

Again you're bringing up irrelevant information. We know from another of Dienekes' recent posts that humans didn't invade the Carribean until relatively recently.

"Colonize" - if there were no previous inhabitants, there's no "invasion". Recent yes, more or less contemporary with Austronesians, right?

No it's not. It's just your assumption. But boats of some sort had obviously been developed by 55k or so because people managed to cross Wallace's Line, but we really have no idea of boating's history before then. Next you'll be claiming that Home erectus had boats.

If they were developed by 55 kya, why not 70 kya? After all they had to cross the Red Sea or at least the Nile, the Indus, the Ganges, etc. before they could arrive to Australia.

Alternativley one could argue that Australian and Papuans did not cross willingly but are nothing but shipwrecked populations carried by one or several storms or tsunamis. Far fetched, I know, but we have no direct evidence that they used boating either and crossing 60 km, towards somewhere you don't even know it does exist, with a bad raft is just not much more likely than being carried by a giant wave, sincerely.

So let's use Occam's Razor and consider what kind of abilities were needed to cross the Red Sea, the Ganges Delta and the wide straits that divided Sundaland from Wallacea and Wallacea from Sahul.

So how did the bow and arrow do it? Or do you believe humans carried the bow and arrow out of Africa when they paddled their dugouts across the Red Sea? -

I do not believe anything but I do not discard that the bow and arrow could also be very old.

You've made so many unjustified assumptions in that short sentence that I don't know where to start. Can you offer any evidence at all that humasn crossed the Red Sea for example? -

MtDNA L6 looks like that.

Anyhow the point is that no matter which path they took they had to cross wide rivers or straits. The Nile itself is a challenge (now swimming in a place so full of crocodiles) but obviously people have been crossing it once and again. There's no archaeological or genetic barrier at that river. Same for the Ganges, Indus, Mekong, Yangtze, Huang He, Narmada, Krishna, etc.

And what about the Danube, Rhin, Dniepr, Dniestr, Don, Bug, Po, Rhone, Garonne, Ebro? What about the Euphrates, Tigris, and Jordan? What about the Congo, Limpopo, and all the other great African rivers? Did people all the time had to climb to the mountains, sometimes many thousands of kilometers away, just to cross a dumb river? Obviously not.

Another of your stupid comments. There's no need for a tsunami, you idiot.

I've seen plenty of insults to various people from you so don't complain when it comes back.

I don't know what you consider an insult but your sentence ("Another of your stupid comments. There's no need for a tsunami, you idiot.") is clearly intended to insult without adding anything at all to the discussion.

It's not just bad manners but also a revelation of your lack of rasonable arguments. When one starts like that is clear that has nothing of value to say and he's just either going mad or trying to provoke the other (or both).

Wow. Is that the best you can do? -

Is this the best you can reply to my main argument that they needed to cross rivers like the Nile without traveling the whole damn Sahara, or like the Ganges without climbing the Hymalayas.

Maju. You comment regarding a tsunami was stupid and deserved a suitably sarcastic comment in return.

"they needed to cross rivers like the Nile."

Not really. They were quite capable of moving up the eastern side if the Nile, although it's not impossible that they were able to cross at times without boats of any sort anyway. Same with the Euphrates, Tigris, Indus and Brahmaputra. Humans seem to have occupied Pakistan and the eastern foothills of the Himalayas quite early and so there is no need to cross the Ganges at all in order to reach SE Asia.

From the comments at other Dienekes sites it seems obvious that surviving Y-haps in the Arabian Peninsular are not remnants of any 'great coastal migration', but rather more recent arrivals. And it also seems obvious that ancient IJ was present early along the Zagros and into Anatolia. They may not derive from an Indian haplogroup but have evolved from,and ultimately replaced, an F haplogroup that eventually entered India. So no need for the postulated 'great coastal migration' at all. There is no need to postulate any sort of basic boating until humans were able to cross Wallacea.

Regarding the tsunami. It's quite on the cards that humans in their boats crossed Wallacea by accident. Boats are frequently blown far from their island of origin in the Pacific. These days the geography of the Pacific is widely known so these castaways can usually return home but in ancient times this was often impossible.

Maju. You comment regarding a tsunami was stupid and deserved a suitably sarcastic comment in return.

A storm or tsunami is a perfectly valid idea, worth considering. And if your concept of "sarcasm" is bluntly calling someone "stupid" and "idiot", then you need to re-learn what sarcasm means.

Not really. They were quite capable of moving up the eastern side if the Nile, although it's not impossible that they were able to cross at times without boats of any sort anyway.

That would mean:

1. to renounce to exploit all the resources at the other bank2. that we would see clear indications of the Nile or other great rivers as genetic and cultural barriers. We do not.

Same with the Euphrates, Tigris, Indus and Brahmaputra. Humans seem to have occupied Pakistan and the eastern foothills of the Himalayas quite early and so there is no need to cross the Ganges at all in order to reach SE Asia

Humans seem to have followed the Narmada-Son route to reach the Ganges and they inhabited both banks of these rivers (and of every other river I can think of).

Even if they would have go up to the brave and frozen waterways of the Hymalayas to cross not one but dozens of rivers that feed the Ganges, in order to reach SE Asia they would still need to cross the Brahamputra and Irrawady or (if they went via the arid steppes) a good deal of other rivers like the Yangtze, Mekong, etc.

You are defending a lost cause: people needed to cross rivers all the time unless they chose to stay in a very limited area (and hope they never suffer a flood). You may not notice now how many rivers and waterways you cross every day you travel, because it's all full of bridges and canalizations, but there was nothing like that in the Paleolithic.

There is no need to postulate any sort of basic boating until humans were able to cross Wallacea.

"that we would see clear indications of the Nile or other great rivers as genetic and cultural barriers. We do not".

Of course we don't now. People in the region have aquired boats.

Your link regarding lion subspecies contains the following:

"which suggests that all sub-Saharan lions could be considered a single subspecies, possibly divided in two main clades: one to the west of the Great Rift Valley and the other to the east".

So the Nile basically separates lions to this day. Admittedly lions don't have boats but you're making the assumption that humans had them before they'd left Africa. But we do know that the emergence from Africa was an extreme bottleneck. Just two surviving mtDNA lines and possibly as few as just one Y-hap.

"Humans seem to have followed the Narmada-Son route to reach the Ganges".

Another assumption.

"Even if they would have go up to the brave and frozen waterways of the Hymalayas to cross not one but dozens of rivers that feed the Ganges".

I'm very tempted to call you an idiot again. You don't need to 'go up to the brave and frozen waterways of the Hymalayas' to cross the many rivers running into the Ganges. Humans have presumably been capable of swimming for quite some time.

Hmmm, the Rift Valley is not the Nile. In fact it has nothing to do with it, except maybe at its sources.

But we do know that the emergence from Africa was an extreme bottleneck.

I don't see it as "extreme", just the usual founder effect. 2/7 L3 sublineages is a significative apportion in fact (28.5% of all L3 diversity at that level). The situation at the Y-DNA level could be even more diverse (50% of the DE or even 75% of the CF'DE).

Another assumption.

No. It is archaeologically documented.

I'm very tempted to call you an idiot again. You don't need to 'go up to the brave and frozen waterways of the Hymalayas' to cross the many rivers running into the Ganges. Humans have presumably been capable of swimming for quite some time.

I'm not going to say what I'm tempted to do because forms do matter. Please research the sources of the Ganges a bit before you make such absurd claims.

2/7 of just the L3s. What about all the other mtDNA lines in Africa at the time? I count at least 15 other lines, and that's just of the ones that survive until today. Two from twenty-two is more like the correct proportion. If humans had possessed boats and were exploiting the supposedly huge resources of the coastal region we would expect there to have been a relatively large and diverse proportion of mtDNA lines to have emerged. Instead we find just two. If that's not a bottleneck I can't imagine what is.

I understand that the population that gave origin to Eurasians was basically (or maybe only) L3 because of drift and all that. I also understand that they might have been the most sea-goers of all, if they lived near Djibuti (H. sapiens idaltu did). The arid lands of Greater Somalia and Eritrea basically invite people to live off the sea and the islands of the southern Red Sea to explore them for resources.

Notice that around Bab-el-Mandeb most of the seafloor is above 200 m depth, what means it was largely firm land in the Ice Ages.

If other peoples used boats at the Congo or Zambezi rivers, lake Tanganyka or wherever, that would have no repercussions regarding Eurasian colonization.

And a bottleneck is a brutal massacre, killing most of the population, not a founder effect. The effects (reduction of genetic diversity) may be similar but the concept is not.

Maju. I think you're going to have to change your mind regarding the impossibility of a Central Asian Paleolithic migration route. Turns out that humans and/or their close relatives have occupied Mongolia, from the Altai mountains in the west to the upper Amur River in the east, virtually continuously since the Lower Paleolithic. Controversial evidence suggests that at times they even moved as far as 60 degrees north, certainly to the region around Lake Baikal. Hopefully Dienekes will be inspired to search out some recent Russian research on the region.

So mtDNA N and Y-hap C could easily have moved through mongolia. I'll grant that the Upper Paleolithic arrived late to the region. But it doesn't necessarily follow at all that the arrival of the first 'modern' humans there coincides with the technology's arrival. Technically the Upper Paleolithic never reached Australia anyway, so we actually have evidence supporting the separation of technology and genes. And we know that language and genes are remarkably independent.

A couple of Dienekes' recent posts, and the discussions there, on the spread of languages and the several lactose-tolerant genes may be relevant. Both have largely spread by introgression through a pre-existing population. Regarding lactose-tolerance Dienekes wrote, 'Its presence in Ireland or India does not strictly require any population movements from Central Europe'. And you said yourself, 'It's just a single allele highly favored by selection: a typical case of introgression: the gene moves and expands where it's selected for but regardless of any population move'. It's advantageous for some populations to possess the lactose-tolerant gene,and individual languages have spread because it became advantageous to learn to speak them.

I'm quite certain you will argue that these two cases are special, but I'm not so sure. Geneticists have been claiming for years that each individual gene behaves in a similar manner to these two cases.

Ultimately perhaps we could think of both Y-haps and mtDNAs behaving in the manner of single genes. They have introgressed into pre-existing populations. The extremely inbred selection of genes that modern humans are often claimed to possess is actually the result of migration, introgression, hybridisation and subsequent selection. To me it's the only explantion that makes sense.

Very interesting but the paper deals with Lower Paleolithic: H. erectus in other words.

The earliest possible dates for the presence of Homo spp. in the area is of 450 kya and more likely 300 kya. This is a late date for the expansion of H. erectus in Eurasia, dating to c. 900 kya and on (600 kya for Europe, for another reference).

The paper actually covers the Middle Paleolithic as well. That's moving away from H. erectus times and the paper even mentions H. heidelbergensis. One of the links claims that the Levallois is earlier in the Mongolian region than it is anywhere else. Possibly originated somewhere near there?

A few days ago I actually found another link dealing with the continuity from the Lower Paleolithic right through to the Upper Paleolithic, but unfortunately I was interupted at short notice and have been unable to find it again. I'll keep looking. Obviously the region has always been ' a marginal area hard to adequate to' but humans seem to have survived in parts of it continuously. They have been able to expand rapidly from those refuges during more moderate times.

H. Heidelbergensis (aka H. Antecessor) is just an evolved erectus in the line to Neanderthal. It says nothing about AMHs.

The steppary corridor offers some possibilities but is "bad" in comparison with tropical/subtropical Asia. Anyhow I must remind you that the area is also crossed by many great rivers, too cold to swim, and that people used to live by those rivers. Even H. erectus may have got some grasp of boating (there's some evidence that they crossed Gibraltar some 600 kya, btw - albeit in a low sea level context).

"The steppary corridor offers some possibilities but is 'bad' in comparison with tropical/subtropical Asia".

Not necessarily so. The jungles of South and SE Asia by no means provide an easy route. Most paleo-anthropologists agree that the prefered ancient human environment was semi-open savanah grassland. Anyway we can be sure that humans of one sort or another have been widespread across, and north of, the Iranian Plateau for a very long time.

"H. Heidelbergensis (aka H. Antecessor) is just an evolved erectus in the line to Neanderthal".

Not just Neanderthal of course. Probably modern humans too.

Regarding your doubts concerning the Middle to Upper Paleolithic transition in Mogolia. All studies on the subject admit to a fairly large level of continuity across the transition. For example this (admittedly 10 year old) link dealing specifically with the Altai:

From the link, 'According to available material, the process of formation of the new cultural stage [Upper Paleolithic] in the region was characterised by a gradual transformation of the Mousterian tradition by introduction of the more progressive Late Paleolithic elements. Presence of the Mousterian and Levallois forms points to the local origin of the Upper Paleolithic industries from the variants of the Altai Mousterian.'

And this link:

http://www.ucpress.edu/books/pages/9850.php

contains the following, 'Until recently, most of the available evidence for this revolution derived from Western European archaeological contexts that suggested an abrupt replacement of Mousterian Middle Paleolithic with Aurignacian Upper Paleolithic adaptations. In the absence of fossil association, the behavioral transition was thought to reflect the biological replacement of archaic hominid populations by intrusive modern humans'.

It continues, 'The contributors present new archaeological evidence that tells a very different story: The Middle-Upper Paleolithic transitions in areas as diverse as the Levant, Eastern-Central Europe, and Central and Eastern Asia are characterized both by substantial behavioral continuity over the period 45,000-25,000 years ago and by a mosaic-like pattern of shifting adaptations. Together these essays will enliven and enrich the discussion of the shift from archaic to modern behavioral adaptations'.

So outside Europe the transition was no simple matter. The Upper Paleolithic is not at all an indicator of the first modern human arrival. It's just that Europe, being better studied that anywhere else, has influenced the general perception.

Finally you may find these extracts (from the same book) regarding the problem of the Middle to Upper Paleolithic interesting:

People was not trying to trek through the World but to survive. They moved only slowly: generation after generation, when the local resources became unable to feed the growing population. From our viewpoint it may seem "fast" but they were in no hurry most of the time. Several, many millennia of the deep past may seem little time for us but, if we think about it all, our written history has not more than a few thousand years in the best case (and a lot of things have happened in such a "short" span).

Not just Neanderthal of course. Probably modern humans too.

That's a controversial opinion at least. For what we can tell from the archaeological record, the lineages of Neanderthals and Humans diverge at H. erectus, almost a million years ago, when some H. erectus began their own OOA adventure.

Regarding your doubts concerning the Middle to Upper Paleolithic transition in Mogolia. All studies on the subject admit to a fairly large level of continuity across the transition.

Well, I am not too knowledgeable on the matter but there are other areas where there is an apparent non-abrupt MP-UP transition (Palestine, India). This is very difficult to interpret and may mean that for a time H. sapiens used Mousterian tools or, alternatively, that Neanderthals (who existed at Altai) were the ones making the transition.

A major issue is the appearence of stone blade tech (that does not derive from Mousterian) but, like in Europe, it may be the case in Asia too that Neanderthals just adopted it and that Sapiens used some Mousterian toolkits too). It's not fully clear at this stage (though I lean towards thinking that UP blade tech was mostly spread by AMHs).

This flow anyhow is very much "Aurignacoid" (some even claim that prto-Aurignacian arose in Altai or otherwise in Central Asia), you just have to look at the tools and you immediately notice that Aurignacian-like style. And the dates are also within the frame of arrival of Aurignacian to Europe, so it seems to reflect a flow connected to the colonization of West Eurasia. Maybe it was the time when Y-DNA Q became consolidated in North Asia (though I guess for many this is way "too old", it does resemble the spread of macrogroup P, which may have been related to this Aurignacoid culture and the spread of blade toolkits).

"They moved only slowly: generation after generation, when the local resources became unable to feed the growing population".

Yes. But people move first through an environment they are familiar with before venturing into what, to them, are less desirable environments. First option for humans all through the Paleolithic would have been grassland containg clumps of trees. Only once the population outstripped resources would they have been forced into the dense jungle.

"For what we can tell from the archaeological record, the lineages of Neanderthals and Humans diverge at H. erectus, almost a million years ago".

I realise you are very wary of accepting DNA dating at face value but mtDNA suggests the separation was more like half a million years ago. That date does fit the spread of the Levallois which seems to be shared between Neanderthals and western elements of H. erectus, although it doesn't spread to the east.

"(though I lean towards thinking that UP blade tech was mostly spread by AMHs)".

I think most would accept that.

"there are other areas where there is an apparent non-abrupt MP-UP transition (Palestine, India). This is very difficult to interpret".

What's interesting here is the level of continuity through Mongolia, and into the Lake Baikal and East Asian regions across the period of its introduction. The same for Palestine and India. This suggests very strongly that the bearers of the UP were not the first genetically 'modern' humans in the region. 'Modern' humans not yet possesssing the UP (and probably not yet possessing Y-hap Q) had already reached the Altai Mountains and Mongolia long before the UP's evolution. How much further had they gone? And before the UP evolved the supposedly superior 'modern' humans seem to have actually adopted the previous residents' lithic technology.

Presumably these pre-UP Central Asian 'modern' humans had not arrived from Africa via any 'Southern Coastal Route', but had probably come through Iran. Along the way they seem to have mixed with the even earlier locals. Ultimately they probably became part of a continuum that reached into Northwest India (and back to Palestine).

So, is it likely that these first 'modern' humans had entered India via a 'Southern Coastal Route'? We can be fairly sure that the Indo-European language entered India from the northwest, via Iran, Afghanistan and Pakistan. The Neolithic, including possibly the Dravidian language, also probably entered via the same route. Do we actually know of any people to have come into Western India by sea, apart from traders?

I still say the 'Southern Coastal Route' is rubbish. A myth. A fairytale concocted to accomodate the Australian Aborigines within another myth: "All humans derive from a relatively recent, suddenly superior, single, small, inbred population; preferably consisting of just a single woman and a single man". In fact most of us appear to believe that each separate species descends from just such single, small, inbred populations. Rubbish.

But people move first through an environment they are familiar with before venturing into what, to them, are less desirable environments. First option for humans all through the Paleolithic would have been grassland containg clumps of trees.

Or first option would be warm climates...

I'd say temperature (not to mention the issue of solar radiation and vitamin D) was a much more important barrier than vegetation types. We are quite flexible and inventive but we are clearly adapted for warm climates (I still "miss" the tropics every single winter). Even as far south as Palestine, winters can be a challenge for the naked ape (and more in the Ice Age) - Siberia was obviously a much more daunting challenge. It is even today!

I realise you are very wary of accepting DNA dating at face value but mtDNA suggests the separation was more like half a million years ago. That date does fit the spread of the Levallois which seems to be shared between Neanderthals and western elements of H. erectus, although it doesn't spread to the east.

Well, it's a possibility but hardly proven. The sad fact is that we don't know enough about the transition between H. erectus and H. sapiens.

What's interesting here is the level of continuity through Mongolia, and into the Lake Baikal and East Asian regions across the period of its introduction. The same for Palestine and India. This suggests very strongly that the bearers of the UP were not the first genetically 'modern' humans in the region. 'Modern' humans not yet possesssing the UP (and probably not yet possessing Y-hap Q) had already reached the Altai Mountains and Mongolia long before the UP's evolution.

It's a possibility but all remains of West/Central Asia for around 60,000 BP are Neanderthals. It would seem that H. sapiens only pushed effectively in that area since c. 50,000 BP. Blade technology is anyhow much older than UP in South Asia (and briefly in Palestine, though apparently associated with Neanderthals) and East Asian UP often lacks blades instead. We should be wary of a too rigid association between blade tech and UP, though they are certainly related in West and Central Eurasia.

Do we actually know of any people to have come into Western India by sea, apart from traders? -

I don't know what you're talking about. "coastal migration" just means along the (very wide) coastal strips of the Eurasian continent. Pakistan and Iran included, or at least their southern halves. As in contrast with "continental migration" via the steppes. The coast is suggestive because it provides food and resources in almost all circumstances but the model does not imply a strict boating migration: that's just an extremist distortion you do.

I still say the 'Southern Coastal Route' is rubbish. A myth. A fairytale concocted to accomodate the Australian Aborigines within another myth: "All humans derive from a relatively recent, suddenly superior, single, small, inbred population; preferably consisting of just a single woman and a single man".

That's just not true. It is widely known that "mithocondrial Eve" was not the only woman of her time, just the one that, quite accidentally, managed to have her mtDNA preserved after drift. You like to caricaturize these issues like if they were mere pseudo-scientific copies of biblical legends but they have nothing to do, even if the name "Eve" is borrowed from that mythology (a mere anecdote).

What is clear is that, genetics dixit, all human maternal and paternal lineages are traced to common ancestors and that is part of the evidence indicating a single shared origin for all Humankind. Inbred or not, at some point H. sapiens were not too many and were a single population living surely in East (or maybe Southern) Africa.

But what is increasingly becoming obvious is that it was no simple transition between 'primitive' and 'advanced' humans.

It's not a terminology I'd use but AFAIK, once H. erectus began having a bigger brain (i.e. significatively bigger than other apes), the trend continued in a rapid fashion and the late H. erectus are already close to our cranial volumes. There may have been some "critical leaps" at some moments (?) but the general trend is to increase the cranial capacity and therefore (at least potentially) the overall inteligence. Anyhow some 1.8 million years ago, H. erectus already had brains of c. 800-900 cc., so the trend towards increased brains (and intelligence) was already going on so long ago and was surely a trait (weakly?) selected for.

That is an extremely wide definition of 'coastal'. In fact it hardly warrants the term.

Fair enough but that's what the issue is about in fact.

The original argument in its favour was that it did involve boats, but we can leave that argument now if you wish.

I think it involved the use of boats, sure: people has always needed some sort of boats and they make foraging much more efficient under most conditions. Additionally they may also help for a faster "strictly coastal" (or riverine) migration but this last is not a crucial point, nor one that is fully clear at the moment. For me it's clear that people has "always" used some sort of boats for crossing rivers, lakes, swamps and, why not?, small stretches of sea in good weather.

"There may have been some 'critical leaps' at some moments (?) but the general trend is to increase the cranial capacity and therefore (at least potentially) the overall inteligence".

I agree. But it is a mistake to equate the expansion of 'modern' humans with the expansion of the Upper Paleolithic. Modern humans had spread through much of Eurasia, including Australia, well before the Upper Paleolithic's appearance. So, in this case, 'modern' humans does not mean a sudden leap into the Upper Paleolithic. I'm not sure what the development of modern humans does mean though, but probably not a 'critical leap'.

By critical leap I was thinking in the alleged increase of brain size that happened c. 600-300,000 years ago with the rise of H. heidelbergensis/antecessor in Europe. Some have argued that around those dates (not sure which) there is a general increase in cranial capacity/intelligence of maybe some 100-200 cc (nothing compared with the leap from Chimpanzee, 350 cc, to H. erectus, almost 1000 cc).

"I was thinking in the alleged increase of brain size that happened c. 600-300,000 years ago with the rise of H. heidelbergensis/antecessor in Europe".

And interestingly that is a date commonly accepted for the separation of the lines leading to Neanderthals and moderns. If the dating is correct it sort of suggests that modern humans descend from a migration INTO Africa about that time. Quite possible, of course.

Well, it's not something I agree with. I cannot fully discard it either, of course.

From c. 1000 cc it's "easy" that both Human species could have evolved in parallel to the 1300-plus we have now. There's not evidence of that migration I know of and the morphological differences between Neanderthals and us are too wide (chest, legs, face... even the shape of the skull) so I'd say we have been diverging for longer, more in the million years range than in just the 600,000 of this hypothetical back-migration. For me the H. erectus that migrated to Europe, either via Gibraltar or West Asia, were the ancestor of Neanderthal, while some of the H. erectus who remained in Africa evolved into us. Other groups would have been less successful, I guess.

Acheulean Levallois may be of African origin in fact. AFAIK it should be derived from the Sangoan/Fauresmith culture(s) of East/South Africa (early Middle Stone Age), which are apparently related with H. rhodesiensis remains, probably transitional between H. erectus and H. sapiens, the same that H. heidelbergensis/antecessor is for Neanderthals.

Regarding the divergence time, I understand that, lacking any other evidence (and rather having substantial evidence of local evolution of Neanderthals in Europe from local H. erectus and transitional forms), the point of divergence should be around when H. erectus migrated out of Africa, that is: c. 900,000 years ago.

If you have substantial evidence of the opposite, I'll be glad to change my opinion.

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